What makes up the
BIOSPHERE?
Energy and water exist and move around the biosphere in different forms
Where does energy come from?
Ecology is studied at very large scales: Biosphere
“A thing is right when it tends to preserve the integrity, stability, and beauty of the biotic community. It is wrong when it tends otherwise” -Aldo Leopold
Painting Chalon Sombrero
Albedo
Global albedo is highly variable
Albedo feedbacks and Snowball Earth
Earth’s average albedo is ~0.3, keeping surface @ 15°C
Do you think albedo is changing?
Albedo: cold generates cold but…..
Sun is the Earth’s primary form of heat energy, via radiation
- ~1/3 of sunlight energy reflects back to space
- Rest is absorbed by land, ocean and atmosphere
- Exact amount absorbed depends on both surface and atmosphere
- The balance of incoming and outgoing radiation makes up Earth Energy Budget
Why clouds are cool…
Atmospheric absorption spectra
Composition of the atmosphere
- Gases have different RESIDENCE TIMES
- N2 = 13 million years
- O2 = 10,000 years
- N20 = 114 years
- CH4 (methane) = 12 years
- CO2 = 5-200 years (1/2 removed quickly)
- Water vapor is reactive and highly variable
- 10 day residence time
- seasonally and spatially
Changes in composition impact atmospheric heating
Water vapor is the most abundant greenhouse gas
- NASA recently confirmed heat-trapping effect of water in the air
- critical component of global change
- collects at tropical latitudes
- 2x climate warming caused by increased CO2
Solar energy & water cycle connected
Water cycle = continuous movement of water within the earth and atmosphere
25% of incoming solar energy leaves the surface through evaporation
Evapotranspiration: Energetics of water movement
- Water has high specific heat
- 4x more energy to heat water than air
- uses up solar energy
- 30% of oceans evaporate per year
- >60% of rainfall is lost to evapotranspiration
- Large energy fluxes when water changes state
- evapotranspiration cools surfaces
- condensation warms atmosphere
Global water cycle: 577,000 km3 of water circulates each year
Global water cycle: Residence times matter
Water for humans?
